Import wiredtiger-wiredtiger-2.4.0-399-g225aa81.tar.gz from wiredtiger branch mongodb-2.8
SERVER-15496 Get rid of replLocalAuth()
SERVER-15496 Update old unit tests to use new ReplicaSetConfig
SERVER-15496 Remove legacy replication code
SERVER-15946 Get rid of GlobalSharedLockAcquirer in favor of taking the global lock directly
SERVER-15946 Don't acquire MMAPV1Flush lock when locking global shared lock for stepdown.
SERVER-15675 Remove OperationContext from UpdateRequest/DeleteRequest

The write execution machinery should have a handle to the operation
context, not the write request structs.
SERVER-15675 PlanStage::invalidate() needs OperationContext

PlanStage::invalidate() is always called by a different thread than
the stage's owning thread.  The method should use the active
OperationContext (the caller's) rather than the stage's
OperationContext.
SERVER-15675 Stages should clear their OperationContext in saveState()

While state is saved, threads pass in their own OperationContext to
invalidate().  When state is restored, the stage will resume with the
OperationContext passed in to restoreState().
SERVER-15861 add secondaryCatchUpPeriodSecs argument to replSetStepDown
SERVER-15946 add repro test for replSetStepDown without force argument will fail if secondaries are behind and there is any write load
SERVER-16200 Reuse already computed field name when iterating
SERVER-15997 Make sure stepdown can be interrupted with killop
SERVER-15986 added storage_engine_metadata - reads and writes storage engine metadata file in data directory
SERVER-15986 prevent server from starting up when non-active storage engine files are detected
             added storage_engine_metadata to mongo/db/storage/SConscript
             fixed cleanbb.py so that cleanup() will remove directories as well.
             fixed unix_socket1.js so that it does not store socket file in data directory
SERVER-15997 Avoid overloading _signalStepDownWaiters
SERVER-15997 Register the ReplicationCoordinatorImpl as a killop listener
SERVER-16248 Disable getIteratorForRepair in WiredTiger
SERVER-16248 fix unit test for getIteratorForRepair